Cerebral palsy (CP) is the most common cause of severe motor impairment in children, affecting 3 per 1000 in the US and internationally. CP has a profound detrimental impact on all aspects of life. Motor impairment is the primary defining feature, but co-occurring developmental disabilities are frequent and lead to a complex array of problems. Approximately 60% of children with CP have some type of communication disorder, however the specific nature of the communication problems in children with CP and how these problems change with development is virtually unknown. Treatment studies are extremely limited, and the evidence base is poor. Creation of research-based tools for classifying speech and language problems in CP and controlled intervention studies are priority areas. In the previous funding cycle, we developed a model for classifying speech and language impairments in children with CP. Our model comprises 4 broad classification groups distinguished on the presence of speech motor involvement with or without the presence of language/cognitive involvement. A key finding is that children with CP show early speech and language development trajectories that are specific to classification groups. This has critical implications for understanding how deficits in language/cognition and speech production interact during development, and for intervention. Age-stratified prospective longitudinal data on children with CP beyond the age of 6 years are not available; thus, rates and limits of change are unknown. This critical barrier impedes our capacity to predict outcomes and develop interventions that optimize speech and language abilities. Our long-term goal is to generate a theoretically driven, data-based longitudinal model of speech and language development in CP that can be used to predict outcomes, test interventions, and guide treatment decisions. The proposed research will extend the longitudinal window of investigation of speech and language development through the age of 10 years in 100 children with CP who we have been following for the past 4 years. Specific aims of the proposed study are: 1.) To quantify longitudinal change in speech and language development and determine stability of classification group membership; 2.) To identify early predictors of later speech intelligibility and classification group membership; and 3.) To test the effects of behavioral speech interventions on intelligibility. Results will have diect clinical implications for communication intervention and will also advance the broader theoretical understanding of CP. The proposed work will validate a longitudinal classification model for communication in children with CP and quantify rates and limits of change of targeted speech and language variables through the age of 10 years. Results will enable us to predict the relative communication abilities of children later in childhood based on data collected earlier in life, and explore the potential benefit of behavioral speech interventions. This will lay a critica foundation for future studies that address behavioral speech and language intervention in the context of developmental trajectories to maximize functional outcomes.